Coke formation during the hydrotreatment of bio-oil using NiMo and CoMo catalysts

In the preparation of hydrogen, the bio-oil from pyrolysis of biomass must be further upgraded (catalytic steam reforming)SO as to improve its quality．However the catalyst used in the steam reforming reaction is easy to lose its activity due to being coked' SO that it is important to study the coke formation and its efects on the catalyst activity in the steam reforming process．Fourier Transform Infrared Spectroscopy were used to analyze the precursor of coke on the catalyst Ni/MgO-La2O3-Al2O3 used in steam reforming reaction and the mechanism of coking Was also discussed based on it．The results indicate that precursors of coke deposited inside the pore of the molecular sieve are mainly paraffin, alcohols, aldehydes and ketones, and aromatic compounds.

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Identification of compounds adsorbed and deposited on the Ni-Mo catalysts surface of alumina and SBA-15 by DRIFTS, Raman and TPO Analyses before and after Guaiacol hydrodeoxygenation.

10.21203/rs.3.rs-321528/v1 ◽

2021 ◽

Author(s):

Rubens W.S. Lima ◽

Thiago L.R. Hewer ◽

Rita M.B. Alves ◽

Martin Schmal

Keyword(s):

Raman Spectroscopy ◽

Deposition Rate ◽

Carbon Deposition ◽

Coke Formation ◽

Supported Catalyst ◽

Organic Substances ◽

Alumina Catalyst ◽

Bio Oil ◽

Before And After ◽

Simple Molecules

Abstract We studied and identified compounds adsorbed or deposited on the catalysts surface of the Ni-Mo supported on alumina and SBA-15, before and after hydrodeoxigenation of a bio-oil model (guaiacol). Marked differences were observed on both catalysts through DRIFTS and Raman spectroscopy showing that the alumina-supported catalyst contains deposits of aromatic and oxygenated organic substances, while the carbon deposits on the SBA-15 as aliphatic simple molecules. TPO analyses confirm that the carbon deposited on the NiMo/SBA-15 catalyst were light polymer types, mainly nanotubes and nano fibers, while on the alumina catalyst the mainly carbon species formed were graphite type and heavier carbons. Post reaction analysis of the catalysts showed coke formation and carbon deposition rate of 1.14 mgcoke.gcat−1 h− 1 for NiMo/SBA-15 and the deactivation was 44 % higher for the NiMo/Al2O3 with 1.65 mgcoke.gcat−1 h− 1of carbon deposition rate.

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Mechanistic Insights into Hydrodeoxygenation of Acetone over Mo/HZSM-5 Bifunctional Catalyst for the Production of Hydrocarbons

Energies ◽

10.3390/en15010053 ◽

2021 ◽

Vol 15 (1) ◽

pp. 53

Author(s):

Kai Miao ◽

Tan Li ◽

Jing Su ◽

Cong Wang ◽

Kaige Wang

Keyword(s):

Hydrogen Pressure ◽

Catalyst Deactivation ◽

Catalyst Activity ◽

Coke Formation ◽

Bifunctional Catalyst ◽

Acid Sites ◽

Coke Deposition ◽

Enhanced Production ◽

Bio Oil ◽

Catalytic Hydropyrolysis

Catalytic hydropyrolysis via the introduction of external hydrogen into catalytic pyrolysis process using hydrodeoxygenation catalysts is one of the major approaches of bio-oil upgrading. In this study, hydrodeoxygenation of acetone over Mo/HZSM-5 and HZSM-5 were investigated with focus on the influence of hydrogen pressure and catalyst deactivation. It is found that doped MoO3 could prolong the catalyst activity due to the suppression of coke formation. The influence of hydrogen pressure on catalytic HDO of acetone was further studied. Hydrogen pressure of 30 bar effectively prolonged catalyst activity while decreased the coke deposition over catalyst. The coke formation over the HZSM-5 and Mo/HZSM-5 under 30 bar hydrogen pressure decreased 66% and 83%, respectively, compared to that under atmospheric hydrogen pressure. Compared to the test with the HZSM-5, 35% higher yield of aliphatics and 60% lower coke were obtained from the Mo/HZSM-5 under 30 bar hydrogen pressure. Characterization of the spent Mo/HZSM-5 catalyst revealed the deactivation was mainly due to the carbon deposition blocking the micropores and Bronsted acid sites. Mo/HZSM-5 was proved to be potentially enhanced production of hydrocarbons.

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Upgrading of Oils from Biomass and Waste: Catalytic Hydrodeoxygenation

Catalysts ◽

10.3390/catal10121381 ◽

2020 ◽

Vol 10 (12) ◽

pp. 1381

Author(s):

Mai Attia ◽

Sherif Farag ◽

Jamal Chaouki

Keyword(s):

Microwave Heating ◽

Alternative Fuels ◽

Fossil Fuels ◽

Coke Formation ◽

High Viscosity ◽

High Oxygen ◽

Conventional Heating ◽

Pyrolysis Oil ◽

High Oxygen Content ◽

Bio Oil

The continuous demand for fossil fuels has directed significant attention to developing new fuel sources to replace nonrenewable fossil fuels. Biomass and waste are suitable resources to produce proper alternative fuels instead of nonrenewable fuels. Upgrading bio-oil produced from biomass and waste pyrolysis is essential to be used as an alternative to nonrenewable fuel. The high oxygen content in the biomass and waste pyrolysis oil creates several undesirable properties in the oil, such as low energy density, instability that leads to polymerization, high viscosity, and corrosion on contact surfaces during storage and transportation. Therefore, various upgrading techniques have been developed for bio-oil upgrading, and several are introduced herein, with a focus on the hydrodeoxygenation (HDO) technique. Different oxygenated compounds were collected in this review, and the main issue caused by the high oxygen contents is discussed. Different groups of catalysts that have been applied in the literature for the HDO are presented. The HDO of various lignin-derived oxygenates and carbohydrate-derived oxygenates from the literature is summarized, and their mechanisms are presented. The catalyst’s deactivation and coke formation are discussed, and the techno-economic analysis of HDO is summarized. A promising technique for the HDO process using the microwave heating technique is proposed. A comparison between microwave heating versus conventional heating shows the benefits of applying the microwave heating technique. Finally, how the microwave can work to enhance the HDO process is presented.

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Hydrodeoxygenation of Guaiacol over Pd–Co and Pd–Fe Catalysts: Deactivation and Regeneration

Processes ◽

10.3390/pr9030430 ◽

2021 ◽

Vol 9 (3) ◽

pp. 430

Author(s):

Nga Tran ◽

Yoshimitsu Uemura ◽

Thanh Trinh ◽

Anita Ramli

Keyword(s):

Coke Formation ◽

Fixed Bed ◽

Fixed Bed Reactor ◽

Regeneration Ability ◽

Co Catalyst ◽

Fe Catalyst ◽

Coke Deposit ◽

Bio Oil ◽

Before And After ◽

Fe Catalysts

In bio-oil upgrading, the activity and stability of the catalyst are of great importance for the catalytic hydrodeoxygenation (HDO) process. The vapor-phase HDO of guaiacol was investigated to clarify the activity, stability, and regeneration ability of Al-MCM-41 supported Pd, Co, and Fe catalysts in a fixed-bed reactor. The HDO experiment was conducted at 400 °C and 1 atm, while the regeneration of the catalyst was performed with an air flow at 500 °C for 240 min. TGA and XPS techniques were applied to study the coke deposit and metal oxide bond energy of the catalysts before and after HDO reaction. The Co and Pd–Co simultaneously catalyzed the CArO–CH3, CAr–OH, and multiple C–C hydrogenolyses, while the Fe and Pd–Fe principally catalyzed the CAr–OCH3 hydrogenolysis. The bimetallic Pd–Co and Pd–Fe showed a higher HDO yield and stability than monometallic Co and Fe, since the coke formation was reduced. The Pd–Fe catalyst presented a higher stability and regeneration ability than the Pd–Co catalyst, with consistent activity during three HDO cycles.

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Coke formation of model compounds relevant to pyrolysis bio-oil over ZSM-5

Applied Catalysis A General ◽

10.1016/j.apcata.2015.12.022 ◽

2016 ◽

Vol 513 ◽

pp. 67-81 ◽

Cited By ~ 49

Author(s):

Shoucheng Du ◽

David P. Gamliel ◽

Marcus V. Giotto ◽

Julia A. Valla ◽

George M. Bollas

Keyword(s):

Coke Formation ◽

Model Compounds ◽

Bio Oil

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Catalyst Stability—Bottleneck of Efficient Catalytic Pyrolysis

Catalysts ◽

10.3390/catal11020265 ◽

2021 ◽

Vol 11 (2) ◽

pp. 265

Author(s):

Jacek Grams ◽

Agnieszka M. Ruppert

Keyword(s):

Lignocellulosic Biomass ◽

Alternative Fuels ◽

Catalyst Deactivation ◽

Coke Formation ◽

Catalyst Stability ◽

Engine Fuel ◽

Lignocellulosic Feedstock ◽

Bio Oil ◽

The Stability ◽

Direct Use

The pyrolysis of lignocellulosic biomass is one of the most promising methods of alternative fuels production. However, due to the low selectivity of this process, the quality of the obtained bio-oil is usually not satisfactory and does not allow for its direct use as an engine fuel. Therefore, there is a need to apply catalysts able to upgrade the composition of the mixture of pyrolysis products. Unfortunately, despite the increase in the efficiency of the thermal decomposition of biomass, the catalysts undergo relatively fast deactivation and their stability can be considered a bottleneck of efficient pyrolysis of lignocellulosic feedstock. Therefore, solving the problem of catalyst stability is extremely important. Taking that into account, we presented, in this review, the most important reasons for catalyst deactivation, including coke formation, sintering, hydrothermal instability, and catalyst poisoning. Moreover, we discussed the progress in the development of methods leading to an increase in the stability of the catalysts of lignocellulosic biomass pyrolysis and strengthening their resistance to deactivation.

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Esterification of Bio-Oil Produced from Sengon (Paraserianthes falcataria) Wood Using Indonesian Natural Zeolites

International Journal of Renewable Energy Development ◽

10.14710/ijred.2021.35970 ◽

2021 ◽

Vol 10 (4) ◽

pp. 747-754

Author(s):

Sri Kadarwati ◽

Evalisa Apriliani ◽

Riska Nurfirda Annisa ◽

Jumaeri Jumaeri ◽

Edy Cahyono ◽

...

Keyword(s):

Relative Concentration ◽

Oil Quality ◽

Coke Formation ◽

Fixed Bed ◽

Acid Number ◽

Natural Zeolites ◽

Total Acid ◽

Interesting Phenomenon ◽

Bio Oil ◽

Total Acid Number

The bio-oil produced from pyrolysis of woody biomass typically shows unfavourable characteristics such as high acidity, hence it becomes highly corrosive. An upgrading process, e.g., esterification, is necessary to improve the bio-oil quality prior to its use as a transportation fuel. In this work, the bio-oil was produced through a fast pyrolysis of Sengon wood in a fixed-bed pyrolyser at various temperatures. The characteristics (density, viscosity, total acid number, relative concentration of acetic acid, etc.) of the bio-oil were evaluated. The bio-oil with the highest acidity underwent an esterification catalysed by Indonesian natural zeolites at 70 oC for 0-180 min with a ratio of bio-oil to methanol of 1:3. The catalytic performance of the Indonesian natural zeolites during the esterification was investigated. A significant decrease in the total acid number in the bio-oil was observed, indicating the zeolite catalyst’s good performance. No significant coke formation (0.002-3.704 wt.%) was obtained during the esterification. An interesting phenomenon was observed; a significant decrease in the total acid number was found in the heating up of the bio-oil in the presence of the catalyst but in the absence of methanol. Possibly, other reactions catalysed by the Brønsted and Lewis acids at the zeolite catalyst surface also occurred during the esterification.

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